Antibody fragments

TLDR

The antibody molecule is modular, allowing separate domains to be extracted, and a wave of novel antigen‑specific molecular forms is expected to enter clinical evaluation. This report examines the developmental histories of therapeutics derived from antigen‑specific fragments of antibodies produced by recombinant processes. Drug developers have explored multi‑specificity and conjugation with exogenous functional moieties across Fab, scFv, and 3G fragment types. The review identified three fragment types—Fab, scFv, and 3G—representing successive waves of technology, but limited data suggest that size alone does not confer distinct clinical properties.

Abstract

The antibody molecule is modular, and separate domains can be extracted through biochemical or genetic means. It is clear from review of the literature that a wave of novel, antigen-specific molecular forms may soon enter clinical evaluation. This report examines the developmental histories of therapeutics derived from antigen-specific fragments of antibodies produced by recombinant processes. Three general types of fragments were observed, antigen-binding fragments (Fab), single chain variable fragments (scFv), and “third generation” (3G), each representing a successive wave of antibody fragment technology. In parallel, drug developers have explored multi-specificity and conjugation with exogenous functional moieties in all three fragment types. Despite high hopes and an active pipeline, enthusiasm for differentiating performance of fragments should, perhaps, be tempered as there are yet few data that suggest these molecules have distinct clinical properties due only to their size.